Keith's Weblog: Comments on "Building large strings in PHP"

by Adam Langley

Sat, 29 May 2004 10:02:22 +0000

Though this is not true in Python.

AGL

by Joshua Paine

Mon, 31 May 2004 00:19:48 +0000

The absolute fastest is to use output buffering. Start a buffer, echo/print everything to output, then pour the buffer into a variable. Slightly but noticeably faster than concatenating--strange but true.

by Keith

Tue, 01 Jun 2004 02:50:55 +0000

Thanks Joshua, I'll have to time it that way as well and publish my results.

by Keith

Sat, 05 Jun 2004 00:32:24 +0000

Hey Joshua, you were right. Not as much of a difference from concatenating to output buffering as it was from building arrays to concatenating, but it did make a difference. Plus, it's often less to type as well. Thanks.

by John Lim

Mon, 07 Jun 2004 16:27:58 +0000

Hi Keith,

Neat trick. I was intrigued enough to check the PHP source code.

A look at output.c shows that ob_start() allocates an enormous 40K buffer for strings. And each time the buffer needs to grow, it does it in chunks of 10K.

John

by Erik

Tue, 08 Jun 2004 04:01:35 +0000

A noob request, but could you show the source code as to how output buffering is done?

The absolute fastest is to use output buffering. Start a buffer, echo/print everything to output, then pour the buffer into a variable

by Keith

Tue, 08 Jun 2004 04:10:53 +0000

No problem. The best thing for me to do is point you to my XML library (source here). I use this technique in the XML_serialize function.

The relevant lines are as follows:


<?php
ob_start();
#output here
$str = ob_get_contents();
ob_end_clean();
return $str;
?>

Or, if you just want to output the string rather than returning it, you can replace ob_get_contents() and ob_end_clean() with ob_end_flush(). You could also replace the combination of ob_get_contents() and ob_end_clean() with ob_get_clean() if you're using PHP 4.3.0 or above. See PHP's documentation at http://php.net/outcontrol

by Claudex

Tue, 08 Jun 2004 08:36:40 +0000

With 100 iterations on my Athlon 2000XP, with Windows Xp:

Append:0.001133
Implode:0.003901
OB:0.000870

by

Fri, 05 Oct 2007 14:28:30 +0000

100 operations? Is that supposed to be funny?

Do at least a billion - counting microseconds is stupid - unless you write "0.001 +/- 100%".

Yes, the error can be this big.

by Php

Thu, 23 Jul 2009 09:53:16 +0000

If absolute fastest use output buffering and use buffer into variable the string concatenating is slightly faster.